“Galvanizing” – What Does It Actually Mean?
In the construction industry, galvanizing refers to a coating process in which materials made of iron or steel are covered with a layer of zinc. Zinc is extracted from natural ores such as zinc blende or smithsonite. After roasting and separating the sulphur content, metallic zinc is produced through electrolysis and then used for coating.
The aim of galvanizing is to protect the metal surface against corrosion and external influences in the long term – a process that significantly increases stability and service life.
Advantages and Areas of Application
Galvanizing gives the workpiece reliable protection against rust and weathering. The major advantage over other coatings: zinc protects not only passively by shielding the material from the environment, but also actively, as it reacts with the iron and forms a protective electrochemical connection.
Galvanized materials are particularly corrosion-resistant and are used in many areas, including:
- Construction – e.g. for balconies, railings or fences
- Vehicle construction – for body parts and trailers
- Mechanical engineering – for screws, nuts and profiles
Overview of Galvanizing Processes
Hot-dip galvanizing (also: batch hot-dip galvanizing)
- The workpiece is immersed in a zinc melt heated to around 450 degrees Celsius.
- Piece galvanizing: Individual components or structures are completely immersed, allowing high layer thicknesses (50-150 micrometres) and therefore reliable corrosion protection to be achieved.
- Continuous galvanizing: Semi-finished products such as profiles pass continuously through a zinc bath, which reduces the corrosion protection because the zinc layer is thinner (up to 40 micrometres) and can be destroyed again in individual places during subsequent processing such as drilling.
- Advantage: High cost-effectiveness and generally strong corrosion protection.
- Disadvantage: Risk of workpieces warping due to the high temperature.
Electrogalvanizing (also: electrolytic galvanizing)
- The workpiece is immersed in an acidic or alkaline electrolyte bath, where chemical processes create a thin zinc layer.
- Frequently used in the automotive industry, as it is a process with high cost-effectiveness.
- Advantage: High precision without drip formation and no warping due to lower temperatures (max. 70 degrees Celsius).
- Disadvantage: Shorter-lasting corrosion protection due to a lower layer thickness of 5-7 micrometres.
Mechanical galvanizing
- The galvanizing process takes place fully automatically in a rotating drum filled with a chemical substance, glass and zinc powder. The glass applies the zinc to the workpiece, and a chemical reaction creates a firm bond.
- Advantage: Suitable for workpieces at risk of warping because there is no thermal influence.
- Disadvantage: Less common in practice because adhesion resistance is significantly reduced.
Thermal spray galvanizing
- A zinc wire is melted, atomised into small particles and then sprayed onto the workpiece.
- Important: Before galvanizing, the corresponding workpiece must be treated with a sandblaster so that the zinc particles adhere to its surface.
- Advantage: Creates long-lasting corrosion protection, even for larger surfaces.
- Disadvantage: Hidden areas are difficult to reach, meaning the process is not suitable for some components.
Did You Know?
Many of our products at METALXACT are already galvanized:
Frequently Asked Questions About Galvanizing
Which galvanizing processes are there?
The most commonly used galvanizing processes are hot-dip galvanizing, electrogalvanizing, mechanical galvanizing and thermal spray galvanizing. There are also many other processes, although some only apply a zinc paint or coating to the workpiece and therefore, strictly speaking, do not produce true galvanizing.
How does a zinc layer protect against corrosion?
Zinc protects in two ways:
Passively: By forming a dense patina that shields the metal from the environment.
Actively: Through an electrochemical reaction in which zinc gives electrons to the iron and thus protects it from rust.
How can galvanizing be removed?
To remove galvanizing, the corresponding workpiece can be placed for several days in a solution of hydrochloric acid, sodium hydroxide or potassium hydroxide. But be careful: there is a risk of damaging the material underneath the galvanized layer as well. For this reason, galvanizing should always be removed by a professional.
Our Conclusion
Galvanizing provides effective and long-lasting corrosion protection for workpieces made of iron or steel. Which process is the right one depends on size, area of application and desired durability.
Whether in construction, mechanical engineering or vehicle construction – galvanized products impress with stability, cost-effectiveness and longevity. With the right method, nothing stands in the way of a permanently protected balcony, fence or body part.